Uptake of adjuvant chemotherapy for colon cancer in older and younger patients in the Irish population.

Abstract

478 Background: Colon cancer is predominantly a disease of the elderly, with recent evidence supporting the use of adjuvant chemotherapy in the older population. However, it remains unclear to what degree such patients are receiving adjuvant therapy in clinical practice. We examined uptake of adjuvantchemotherapy and it’s impact on survival in older patients with stage II and stage III colon cancer in a national cohort. Methods: Using the National cancer Registry of Ireland, we identified 3,486 patients with stage II and III colon cancer who were treated with curative resection from 2004-2009. Clinopathological features and chemotherapy use were compared between those ≥70 years and those < 70 years. Results: A total of 2,026 patients with stage II disease were identified, 56% male and 60% ≥ 70 years. T3 tumors accounted for 81%, T4 19% and 89% were grade 2/3. Adjuvant chemotherapy was utilized in 10% and 40% of ≥ 70 and <70 years, respectively (p<0.0001). A benefit for chemotherapy over observation alone was seen in both the older [HR 0.36; 95% CI 0.36 – 0.68; p <0.0001] and younger patient groups [HR 0.43; 95% CI 0.2701 - 0.6881; p<0.0004]. Of 1,460 patients with stage III disease, 51% were ≥ 70 years, 54% male. 34% of older and 83% of younger patients received adjuvant therapy (p<0.0001). A similar magnitude of benefit from chemotherapy compared to observation was seen in patients ≥ 70 years [HR 0.30; 95% CI 0.29 - 0.45 ; p <0.0001] and <70 years [HR 0.22 95%CI 0.1 – 0.2; p<0.0001] with stage III disease. Conclusions: Adoption of adjuvant chemotherapy appears to be associated with significant survival benefit in older patients (age ≥ 70 years), however, is still underutilized in clinical practice. The impact of sociodemographic and clinicopathological features as potential drivers of treatment decisions in a cohort of this population will be reported.